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Updated from Qt4 to Qt5 -> QtCore4.dll is missing

  • Hey,

    i was using Qt4 for a while and now updated to using Qt5, but my application won't start, saying:

    "The program can't start because QtCore4.dll is missing from your computer. Try reinstalling the program to fix this problem."

    • I'm using the Qt5 Visual-Studio Add-In

    • my Qt-folder is located at C:\qt\5.0.2

    • in Visual-Studio Qt-Options: QT_5.0.2, C:\qt\5.0.2\qtbase

    • project's Qt-Version is QT_5.0.2

    • i added the user environment variable QT_DIR with key C:\qt\5.0.2

    • in project settings i added "additional include directories":

    and also $(QT_DIR)\qtbase\include

    • in project settings i added "additional library directories":


    • in project settings i added "additional dependencies":


    I have no idea, why it still keeps asking for the QtCore4.dll. Can anybody help?

  • Moderators

    Did you:

    Clean your build tree, and

    Recompile your project?

    Uninstalling Qt 4 before doing that could also help

  • Here is my solution what worked for me so far: I opened up the Task Manager, clicked on "Start Up", and simply chose "disable Daemon". Since then I don't see this annoying pop-up message! :-)

  • Is it possible that in your application you are using some third party dll compiled with a previous version of Qt? Something like Qwt or Scintilla?

    My suggestion is using DependencyWalker (http://www.dependencywalker.com/). If you run it and load the compiled executable it should be rather easy to see where the Qt 4 core dll is referenced.

    • oops I see now that this is an old post :)

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